1. Field of the Invention
The present invention relates to an IC card formed by mounting an IC (Integrated Circuit) on a circuit board and molding them with resin.
2. Description of the Related Art
FIG. 1A is a plan view which illustrates a conventional IC card, and FIG. 1B is a cross-sectional view which illustrates the same. An integrated circuit 1 (abbreviated as "IC" hereinafter) is mounted on a reverse side of a circuit board 2 and connected to a circuit (not shown) formed on the same side of the circuit board 2. A plurality of electrode terminals 3 for establishing an electrical connection between the IC 1 and external equipment is disposed at an end portion of the inverse side of the circuit board 2, that is, the obverse side of the same. The electrode terminals 3 are connected to the above circuit formed on the reverse side of the circuit board 2. Thus-formed circuit board 2 is fitted and bonded, with an adhesive (not shown), within a recessed portion formed in a card base body 4 composed of molding synthetic resin, to expose the obverse side of the circuit board. In an another method for assembling of the IC card, as shown in FIGS 2A and 2B, the thus-formed circuit board 2 is molded by sealing with resin as follows: first, the circuit board 2 is, as shown in FIG. 2A, disposed within a recessed portion 5a of the lower mold 5 such that the side on which the electrode terminal 3 is disposed is faces downward and the two ends thereof are respectively supported by a pair of positioning projections 5b. Then, the circuit board 2 is fixed within the recessed portion 5a by reducing pressure through a suction hole 5c. Next, as shown in Fig. 2B, an upper mold 6 is secured to the lower mold 5. Then, molten synthetic resin is introduced through a runner 5d and injected into the recessed portions 5a and 6a. Thus, as shown in FIG. 1, an IC card in which the circuit board 2 is embedded in the card base body 4 and integrated with the latter is completed with the obverse side of the circuit board 2 esposed.
In the conventional IC card formed as described above, a problem arises from adhering the circuit board 2 to the IC 1. The IC 1 is secured to the reverse side of circuit board 2 in the recessed portion of the card base body 4 which has been previously molded. The problem is deterioration of the adhesion and water invasion from outside to the adhered portion. On the other hand, an IC card formed by integrally embedding one side of the circuit board 2 with synthetic resin cannot be readily secured to the mold. In addition, a large portion of one surface of the IC card 1 covered by the obverse surface of the circuit board 2, which harms the appearance of the IC card. It as well causes a problem in that it is difficult to apply a print or the like to the surface, and caused a limitation in terms of design of the IC card. Another problem arises, due to the fact that the surface of the circuit board 2 is exposed on one surface of the card base body 4, in that the card can be warped due to the difference between the thermal expansion coefficients of the circuit board 2 and the card base body 4. As a result, bond strength between the circuit board 2 and the body 4 deteriorates.